Means for securing heat-indicators to oven-doors



(No'MbdeL) D. G. LITTL'EPIELD.

MEANS FOR SECURING HEAT INDIGATORS TO OVEN DOORS.

No.550,349.- Patented Nov. 26, 1895.

El E. :1 x J) I :1 venz'or.

AN DREW EGHAHAM. PHOTO LI'I'MQWASHING'I'DNIC attorney UNITED STATES PATENT OFFICE.

DENNIS G. LITTLEFIELD, OF ALBANY, NEW YORK.

MEANS FOR SECURING HEAT-INDICATORS TO OVEN-DOORS.

SPECIFICATION forming part of Letters Patent No. 550,349, dated November 26, 1895.

Application filed A ril 11, 1895. Serial No. 545,406. (No model.)

To aZZ whom it may concern.-

Be it known that LDENNIS G. LITTLEFIELD, a citizen of the United States, residing at Albany, in the county of Albany and State of New York, have invented new and useful Improvements inMeans for Securing Heat-In dicators to Oven-Doors, of which the following is a specification.

My invention relates to means for securing heat-indicators in place in doors or ovens, so that heat from the oven may have contact with all portions of the body of the same and atmosphere from without will be prevented from reducing the temperature of the body portion of the indicator.

The object of my invention is to provide means by which the body of the heat-indicator may be held fully exposed to the heat of the oven and the oven-door be lined to prevent loss of heat by radiation, and the outer closing-cap holding the dial and glass be kept cool and be made to have a tight joint with the body of the indicator, and the indicator be readily removed at will without removing the lining-plate of the oven-door. I attain this object by the means illustrated in the accomcompanying drawings, forming a part of this specification, in which Figure 1 is a view of an oven-door from its inner side with part of its lining-plate broken away and having secured in place in the door a heat-indicator with part of the case broken away to expose a portion of the hidden operating devices. Fig. 2 is a sectional View of the oven-door and its lining-plate and a side view of the heat-indicator, and Fig. 3 is a transverse sectional view taken at line 1 in Fig. 1.

The same letters of reference refer to like parts throughout the several views.

In the drawings, A represents the ovendoor, which door may consist of asingle plate or be composed of two plates a a, as shown in Fig. 2, and is provided with a central opening a of size and form suitable for receiving the dial end of the heat-indicator.

B is the heat-indicator, which may be of any suitable construction and provided with a dial end I), with which the central opening a corresponds, which end projects through said opening in the door as may be sufficient to expose to view the dial D and the pointer (Z.

Heretofore the inner end portion 1) of the indicator was exposed to the heat of the oven, while the body portion 19 of the indicator was wholly inclosed between the ovendoor plate and the inner lining-plate, so that heat from the oven could not have contact with said body portion 19 Further, heretofore, the dial end portion of the indicator could not make a close joint with the annular edge of the opening c receiving said end portion, but was so open as to admit air from without to permit it to effect a reduction of the temperature of the body portion of the indicator contained between the oven door plate and the lining-plate of the door. This exposure of onlythe inner end portion of the indicator to the heat of the oven and the exposure of the body portion of the indicator to the action of a reduced temperature of outer atmosphere operate to prevent the heat from the oven to so affect the operating parts of the indicator that they are prevented from indicating the true temperature of the oven. These defects are remedied by my invention by the following-described means: I provide the body portion 19* of the heat-indicator with the end closing-cap O, which nicely fits the outer end margin of the wall of said body portion and binds the glass front Wall d on the outer end edge of said portion. This closingcap 0 is provided with the annular flange c. A gasket D, preferably of asbestos, is interposed between said flange and the inner side of the metal adjacent the central opening a A is the lining-plate of the door andis made with a central depression A which is eX- tended toward the plate or plates constituting the door A sufficiently to allow the inner end portion 1) of the heat-indicator to be contained wholly within said recess without projecting out therefrom and past the line of the plane of the inner side of the said lining-plate A toward the oven 0. At the bottom of this depression A is the central perforation e, of diameter greater than that of the body portion 19 of the heat-indicator, so as to leave a clear opening 6 all around between the wall of said body portion of the indicator and the annular edge of said perforation 6, through which opening heat from the oven may freely enter to have contact with the wall of said body portion 11 Bosses E E on the depressed portion of this lining-plate A, at two or more points, serve as means for raising the coupling-plate F above the plane of the bottom line of the central depression A and thereby provide an opening 6 between said coupling-plate and the depressed wall portion of said lining-plate for allowing heat to freely pass to the opening 8 for contact with the body of the indicator. Screws 8 5, (having preferably asbestos washers beneath their heads,) passing through the coupling-plate F and bosses E E and screwing into the metal of the door, securely hold the indicator B in place in the door with its entire body exposed to be affected by the heat of the oven,while atmosphere from without is wholly excluded. The asbestos packing or gasket D prevents the heat from the oven from materiallyheating the outer wall of the closingap O and thereby expand the same, while at the same time the heat from the oven will so affect the wall of the body portion of the indicator as to expand said wall and thereby cause the joint between said body portion 1) and cap to be made close and tight. Further, the heatindicator may be at any time readily removed or replaced without removing the lining-plate A of the door, as access to the holding-screws s 8 may be had at all times.

Having described my invention, what I claim, and desire to secure by Letters Patent, 1s

1. The combination with an oven-door provided with central opening a and a heat-indicator having its dial end in said central opening, of the closing cap C provided with the annular flange c and nicely fitting on the dial end of the body portion of said indicator and the gasket D between said flange and the metal of the door adjacent said central opening, substantially as and for the purposes described.

2. The combination with an oven door provided with central opening :1 a heat-indicator having its dial end in said central opening so as to be viewed from the outside of said door, a closing cap provided with annular flange 0 and gasket D, of the lining-plate A provided with depression A having at its bottom the central perforation e of diameter greater than that of the body portion of the indicator and the coupling plate F and holding devices 8 s substantially as and for the purposes set forth.

3. The combination with oven-door A, having central opening a and a lining plate having in it depression or recess A in which is made central perforation e of the heat indicator B having its dial end within the opening a a radial flange 0 connected with the body portion of said indicator, gasketD between said flange and the metal adjacent said opening a opening 6 annular to the body portion of the indicator, coupling plate F secured to the depressed wall portion of said lining plate, and opening 6 substantially as and for the purposes set forth.

DENNIS G. LITTLEFIELD. \Vitnesses ALEX. SELKIRK, O. XVM. DOTTERMUSCH. 

